This application relates to the field of compositions for the treatment of oily skin, more specifically to a topical treatment for the skin to reduce sebum.
There are three major facial skin types: (1) skin that is slightly to extremely oily; (2) skin that is slightly to extremely dry; and (3) skin that is slightly to extremely oily across the forehead and down the nose to the chin (the so-called T-zone) and simultaneously slightly to extremely dry across the rest of the face.
In order to treat dry skin to reduce the tightness, flakiness and scaliness, humectants and emollients are used.
However, there are no such ready treatments for oily skin. Skin oils, which are properly called sebum, can be removed by applying low molecular weight alcohols, such as ethyl alcohol or isopropyl alcohol. Alternatively, the skin can be cleansed with soaps or surfactants. Usually, these techniques offer only a temporary reprieve from the oiliness, since the removed sebum is readily replaced by an abundant reservoir of oil residing in the sebaceous glands just below the surface of the skin.
Sebum is a secretion of the sebaceous gland. This gland is found in the epidermis of the entire body except for the palms of the hands, the soles and dorsal (upper) surfaces of the feet. They are found in their highest numbers on the head, particularly on the face and the scalp (Strauss, J. S. and Pochi, P. E. In: Gans, O., Steigleder, G. K., eds. Hanbuch der Haut-und Geschlechtskrankheiten; Normale und Pathologische Anatomie der Haut I. Berlin: Springer-Verlag, 1968:184-223; Wilkinson, J. B. and Moore, R. J., eds. Harry""s Cosmeticology, 7th ed. New York:Chemical Publishing, 1982). The amount of sebum produced by these glands is controlled by endogenous hormones, especially particularly the sexually related hormones such as testosterone, and therefore varies from one individual to another. Sebum flow is also controlled by a variety of other factors, such as temperature and humidity (Stauss, J. S., Downing, D. T., and Ebling, F. J. In: Goldsmith, L. A., ed. Biochemistry and Physiology of the Skin. New York: Oxford University Press, 1983:569-595).
Hormonal control is at least partially under the influence of an enzyme, namely 5-alpha reductase, that converts testosterone to dihydrotestosterone, which effects the production of sebum. Levels of sebum produced by the sebaceous glands are normally highest during the teenage years. In women, the output of sebum normally decreases after menopause. The level remains relatively unchanged into old age in men (Pochi, P. E., Strauss, J. S., and Downing, D. T., J. Invest. Dermatol. 73:108-111(1979)).
Sebum is composed of triglycerides, diglycerides, free fatty acids, wax esters, squalene, cholesterol and cholesterol esters (Greene, R. S., Downing, D. T., Pochi, P. E., and Strauss, J. S., J. Invest. Dermatol. 54:240-247(1970)). Although the function of sebum is believed to be primarily in helping to maintain the skin""s barrier integrity, it also is known to have mild bactericidal and antifungal properties (Kligman, A. M. In: Montagna, W., Ellis, R. A., and Silver, A. F., eds. Advances in Biology of Skin:The Sebaceous Glands, Oxford, England: Pergamon Press, 1963: 110-124). Sebum is also well know to protect the hair shaft from damage brought about by brushing, combing and styling of the hair (Agache, P. G. In:Zviak, C., ed. The Science of Hair Care. New York: Marcel Dekker, 1986: 469-500).
There are two primary ways that sebum is believed to affect the severity of acne. The first is that excess sebum can contribute to the packing of horny skin cells at the opening of the sebaceous follicle on the surface of the skin. This abundance of dead skin cells causes a constriction in the follicular opening ultimately leading to a plug or comedone.
A comedone is one of the earliest physical manifestations of acne. Furthermore, once the comedone is formed, regardless of its origin, it is normally found to be populated with an anaerobic microorganism, namely Propionibacterium acnes (P. acnes). The sebum in the follicle provides an excellent growth medium for this organism. The products of the growth of P. acnes on sebum results in the generation of free fatty acids that are irritating to the skin and have been shown to be acneogenic. If a break in the thin walls of follicle occurs, these microbially-derived irritants can escape into the surrounding epidermal and surrounding dermal tissue producing significant irritation and therefore redness and tissue damage. This latter effect of sebum on acne is believed to be one of the principal sources of the redness of acne.
Therefore, for both cosmetic and dermatological reasons, the ability to reduce the presence of sebum on the skin is important. An even greater effect would be to reduce the amount of sebum on the surface of the skin initially as well as to reduce it for a significant period of time following a topical treatment.
Thus, a significant amount of research has been devoted to identifying ways to reduce sebum on the skin. Many different approaches have been tried, most with only limited success. The primary approach has been to try to avoid putting oils on the surface of the skin. Such xe2x80x9coil-freexe2x80x9d approaches have met with little success. However, by providing products to apply to their skin that do not feel oily or greasy, consumers believe that they are taking positive steps to avoid making the skin more oily than normal.
Numerous products have been developed that contain materials to absorb the oils secreted by the sebaceous glands. These products contain materials such as starches, clays, silica, and even porous polymer beads that bind surface skin oils. Although these products actually exhibit some efficacy in absorbing sebum, they are difficult to deliver to the skin in sufficient quantities to absorb a significant quantity of sebum without radically detracting from the form or feel of the formulation. Therefore, this method of sebum reduction often results in products that are either less effective than needed or less aesthetically appealing to consumers. Therefore, there is a definite need for better, more technically advanced methods to reduce sebum on the skin.
Currently techniques for treating oily skin offer only a temporary reprieve from the oiliness, since the removed sebum is readily replaced by an abundant reservoir of oil from the skin. For both cosmetic dermatological reasons, the ability to reduce the presence of sebum on the skin is important. Described herein are novel compositions and methods which reduce the amount of sebum on the surface of the skin after initial application, and continue to reduce the presence of sebum on the surface of the skin for a significant period of time following a topical treatment.
A method of reducing sebum on the surface of skin is provided. The method includes applying topically to the skin a composition that includes an alcohol, pyridoxine hydrochloride or a salt or derivative thereof, and a zinc salt, wherein the composition is applied to the surface of the skin in an amount sufficient to reduce sebum.
In one embodiment, the method includes applying a composition that includes alcohol as about 0.01 to 40% by weight of the composition, pyridoxine hydrochloride, or a salt or derivative thereof, as about 0.00001% to 5% by weight of the composition, and zinc salt as about 0.0001 to 10% by weight of the composition. In one specific, non-limiting example, the alcohol is present as about 10% by weight of the composition, the zinc salt is present as about 0.5% by weight of the composition, and the pyridoxine hydrochloride is present as about 0.05% by weight of the composition.
Other embodiments also include a topical composition for reducing sebum on the surface of the skin, wherein the composition includes an alcohol, pyridoxine hydrochloride or a salt or derivative thereof, and a zinc salt in an amount sufficient to reduce the amount of sebum on the surface of the skin.
In another embodiment, the composition includes alcohol as about 0.01 to 40% by weight of the composition, pyridoxine hydrochloride, or a salt or derivative thereof, as about 0.00001% to 5% by weight of the composition, and zinc salt as about 0.0001 to 10% by weight of the composition. In one specific, non-limiting example, the alcohol is present as about 10% by weight of the composition, the zinc salt is present as about 0.5% by weight of the composition, and the pyridoxine hydrochloride is present as about 0.05% by weight of the composition.